James dick gilmour



(No Model I J. D. GILMOUR.

PROCESS OF MAKING UYANIDS.

v No, 576,264. v Patented Feb 2, 1897:.

NITED STATES PATENT ()FrIcE..

JAMES DICK GILMOUR, OF GLASGOTV, SCOTLAND.

PROCESS OF MAKING CYANIDS.

SPECIFICATION forming part of Letters Patent N 0. 576,264, dated February 2, 1897.

Application filed October 9, 1893. serial No. 487,631. (No specimens.) Patented in England December 81,1892, No. 24,116.

To all whom it may concern:

Be it known that I, J AMES DICK GILMOUR, of Glasgow, Scotland, have invented certain Improvements in the Manufacture of Cyanids and Cyanogen Compounds, (patented in Great Britain December 31, 1892, No. 24,116,) of which the following is a specification.

In the accompanying drawings, Figure 1 is an elevation, and Fig. 2 a diagrammatic plan, of an apparatus or plant which I prefer to employ in carrying out my invention.

In said drawings, A represents a retort or vessel heated from without and in which the raw material (carbon and alkaline carbon ate) are heated by means of a furnace A.

B represents a cooling-chamber into which the hot material from the retort A is conveyed by a screw conveyer b.

0 represents a truck employed to convey the material from the chamber B to a platform C, which is arranged above a lixiviating-tank D, which is provided with a filter or false bottom.

D is a tank in which the liquor which passes through the tank 1) may be collected.

E is a still connected by a pipe c with an absorbing tank or vessel L.

F represents a furnace in which is produced carbon dioxid, and connected with the still E by a pipe 2.

g is a condensing-worm situated in a cooling-tank G and connected with the still, and through which the vapors from the still pass.

G is a receiver into which the products of condensation from the said condensing-worm pass.

H is a jacketed still or vessel heated from without, as by means of steam from a boiler T, conveyed to the jacket of the said still through a pipe U. A pipe 3 connects the receiving-vessel G with the still H.

J indicates a series of condensers connected by pipes 4 with the still H and by a pipe 6 with a receiver K, the products from condensation from said condensers passing through this pipe into the receiver K.

K represents an inverted bell or tank, the open end of which is immersed in the liquid contained in the receiver K.

The absorber L is connected by a pipe 5 with the upper portion of the receiver G, and

in turn its upper portion is connected by a R represents a truck into which the mate-' rial passing through the chute may bedelivered, the truck being lifted by the elevator S onto a platform S, so that its contents may be discharged into the retort A.

V represents the chimney-stack.

In carrying out my invention I make a mixture of about equal parts of carbon or carbonaceous matter (preferably wood, 1'. a, sawdust or wood-charcoal) and an alkaline hydrate or carbonate, or alkaline earth, that is to say, potassium sodium, calcium, strontium or barium hydrate or carbonate, ora

mixture of any of these, but preferably potas-.

sium carbonate. The quantities may be varied from one part of the carbonate or hydrate ofthe above metals to two parts of the carbon, or vice versa. This mixture is heated in suitable vessels to about 1,000 centigrade, but this may vary, and a current of atmospheric nitrogen, more or less deprived of free and combined oxygen, is passed over or through the mixture until the said mixture is more or less converted into a cyanid. The vessel is emptied and the contents cooled and lixiviated with water when the cyanid comes into solution. A current of carbon dioxid is then passed through the solution, preferably at a boiling temperature, when hydrocyanic acid. distils off and is condensed by means of a suitable coil and drops into a suitable receiver, after which it is rectified or concentrated and added to a strong solution of caustic soda, when sodium cyanid crystallizes out, or it may be added to a strong solution of caustic potash, when potassium cyanid crystallizes out. The carbon dioxid for the displacement of the hydrocyanic acid is obtained by the combustion of carbon with atmospheric air, the carbon dioxid being absorbed or combined according to the equation CO +II O+2KCL EZHCN-l- K CO The remaining nitrogen passes to the retort to form cyanid with a fresh quantity of the aforesaid mixture. lVhen all the cyanid has been displaced by the carbon dioxid as hydrocyanic acid, the solution of po tassium carbonate is then evaporated to dryness and used in a fresh operation in the retort. The carbon dioxid is obtained from the combustion of carbon in atmospheric air, which serves three advantageous purposes: first, the air is deoxidized, so that the nitrogen thereof may be used in the retort to treat the first-described mixture; second, the cyanid is changed to hydrocyanic acid, and, third, the regeneration of the alkali.

The manner in which my process is carried out in the apparatus shown in the drawings will now be described. The mixture of carbonaceous material and alkali is heated in the retort or vessel A, through which I pass a current of atmospheric nitrogen. After the cyanid has been formed in the retort, which takes from six to ten hours, it is withdrawn into the cooler B by means of any suitable conveyer, from which it is transferred by means of trucks 0 and a hoist or lift (not shown in the drawings) to a platform, where the trucks are tipped so as to empty their contents into the tank or vessel D,which contains water. After being lixiviated in said vessel D, where the cyanid comes into solution, itis then filtered through a cloth or other filter into a tank D. The cyanid solution contained in D is then pumped or otherwise conveyed into the vessel L, which vessel is connected with the vessel E by means of a pipe 8, provided with a stop-cock, so that E can be refilled from L at will. The solution in the vessel E is then treated or scrubbed with a current of carbon dioxid (obtained by the combustion of carbon with atmospheric airin an ordinary furnace F) and at the same time heated, preferably, to a boiling temperature by steam led from a boiler T by a pipe U, when hydrocyanic acid and aqueous vapor dist-i1 over and are condensed in a worm g, contained in vessel G, from which it drops or falls into a receiver G. The nitrogen and any remaining carbon dioxid which has not entered into combination now pass on through the pipe 5 to the Vessel L, where the remaining carbon dioxid is absorbed, and any caustic potash resulting from the lixiviation of the contents of the retort is thereby con verted into carbonate, which also helps to prevent the decomposition into ammonia when the solution is run into E and treated. The nitrogen now passes on to M and thence to M, which contain water, where it is freed from any hydrocyanic acid which may have been carried over from L. The nitrogen is now passed on to the retort by means of the pump or blower N to form a fresh quantity of cyanid. \Vhen all the hydrocyanic acid has been distilled off from E and collected in G, the solution of potassium carbonate is then pumped or otherwise conveyed to evaporating-pans P, where it is evaporated to dryness by the waste heat from the retort A, after which it is mixed with the residue, chiefly carbon, which is taken from the vessel D after the cyanid solution has been filtered off. The residue from the vessel D is conveyed by means of a chute G into a truck R and conveyed to a hoist S and used in a fresh operation in the retort. E is then refilled by the already highly carbonated solution from L, and L refilled from D, and so 011.

It may be here mentioned that during the heating of E the steam of carbonic-acid gas must be kept passing; otherwise the cyanid will decompose into ammonia.

The aqueous solution of hydrocyanic acid in the receiver G is run into a steam-jacketed or otherwise heated vessel or pan H, from which it is distilled and rectified or concentrated by a suitable set of condensers J and forced over into the vessel K, where it meets a concentrated solution of caustic soda and forms sodium cyanid which crystallizes out.

The caustic soda must not be less in strength than thirty-five per cent. of volume and the hydrocyanic acid not less than forty per cent. by volume, the parts of caustic soda and by drocyanic acid being fifty-four and sixty per cent. by weight, respectively. If these conditions are not attended to, no crystallization will take place. lVhen caustic potash is used instead of caustic soda, it must not be less in strength than forty per cent. volume and the hydrocyanid not less than forty-five per cent. by volume.

As hydrocyanic acid is very poisonous, it is obvious that the last operation cannot be performed in open vessels. Accordingly the vessel K is provided with a hell or inverted cylinder K, the mouth or open end of which dips into the caustic solution in K. The air in K is now exhausted by means of an air-pump (not shown in the drawings) until the solution rises to within two or three inches of the top. The hydrocyanic acid is then delivered at the bottom, or nearly so, of K, so that it cannot escape. During the combination heat is developed. On cooling the cyanid of sodium crystallizes out and falls to the bottom of the vessel K, from which it is fished out.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is-- 1. In the art of manufacturing cyanogen compounds, the herein described process which consists in passing carbon dioxid and atmospheric nitrogen through a solution of a cyanid, forming hydrocyanic acid and a car-. bonate of the base of the cyanid, substantially as set forth.

2. In the art of manufacturing cyanogen compounds, the herein described process which consists in passing carbon dioxid and atmospheric nitrogen through a solution of a cyanid, forming hydrocyanic acid and a car- ICC) bonate of the base of the cyanid, then separating such acid and carbonate, drying the carbonate and mixing it with carbonaceous material and passing through such mixture, while maintained at a high temperature, the nitrogen freed from the said carbon dioxid, substantially as set forth.

In the art of manufacturing cyanogen compounds, the herein described process which consists in treating a mixture of carbonaceous material and an alkali at a high temperature with nitrogen forming a cyanid, lixiviating such cyanid, passing through the solution of the cyanid carbon dioXid and nitrogen while the solution is at a high temperature, forming hydrocyanic acid and a JAMES DICK GILMOUR.

Witnesses JAMES YATE JOHNSON, JOHN GEORGE CLARK. 

